Melatonin, N-aceyl-5-methoxytryptamine, is the main secretory product of the pineal gland and has neuroprotective effects on several brain injuries, including ischemic stroke. In the present study, we hypothesized that exogenous melatonin may decrease hypoglycemia-induced neuronal death through the prevention of superoxide generation. To test our hypothesis, hypoglycemia was induced by injecting human insulin (10 U/kg, i.p.) in rats. Melatonin injection was started immediately after hypoglycemia (10 mg/kg, i.p.). The first melatonin injection was performed at the end of a 30-min isoelectric EEG period. The second and third injections were administered at 1 and 3 h after the first injection. Reactive oxygen species generation, as detected by dihydroethidium staining, was significantly reduced by melatonin treatment. Neuronal injury was reduced by the treatment of melatonin in the hippocampal CA1 and dentate granule cells. Microglia activation was robust in the hippocampus after hypoglycemia, which was almost completely prevented by melatonin treatment. Hypoglycemia-induced cognitive impairment was also significantly prevented by melatonin treatment. The present study suggests that melatonin has therapeutic potential to prevent hypoglycemia-induced brain injury.

Keywords:
Hypoglycemia, Insulin, Melatonin, Rats, Zinc, Superoxide, Microglia
1.
Davis EA, Keating B, Byrne GC, Russell M, Jones TW: Impact of improved glycaemic control on rates of hypoglycaemia in insulin dependent diabetes mellitus. Arch Dis Child 1998;78:111-115.
2.
Auer RN, Olsson Y, Siesjo BK: Hypoglycemic brain injury in the rat. Correlation of density of brain damage with the EEG isoelectric time: a quantitative study. Diabetes 1984;33:1090-1098.
3.
Hershey T, Craft S, Bhargava N, White NH: Memory and insulin dependent diabetes mellitus (IDDM): effects of childhood onset and severe hypoglycemia. J Int Neuropsychol Soc 1997;3:509-520.
4.
Suh SW, Aoyama K, Chen Y, Garnier P, Matsumori Y, Gum E, Liu J, Swanson RA: Hypoglycemic neuronal death and cognitive impairment are prevented by poly(ADP-ribose) polymerase inhibitors administered after hypoglycemia. J Neurosci 2003;23:10681-10690.
5.
Suh SW, Hamby AM, Swanson RA: Hypoglycemia, brain energetics, and hypoglycemic neuronal death. Glia 2007;55:1280-1286.
6.
Suh SW, Gum ET, Hamby AM, Chan PH, Swanson RA: Hypoglycemic neuronal death is triggered by glucose reperfusion and activation of neuronal NADPH oxidase. J Clin Invest 2007;117:910-918.
7.
Suh SW, Garnier P, Aoyama K, Chen Y, Swanson RA: Zinc release contributes to hypoglycemia-induced neuronal death. Neurobiol Dis 2004;16:538-545.
8.
Suh SW, Aoyama K, Matsumori Y, Liu J, Swanson RA: Pyruvate administered after severe hypoglycemia reduces neuronal death and cognitive impairment. Diabetes 2005;54:1452-1458.
9.
Choi BY, Kim JH, Kim HJ, Yoo JH, Song HK, Sohn M, Won SJ, Suh SW: Pyruvate administration reduces recurrent/moderate hypoglycemia-induced cortical neuron death in diabetic rats. PLoS One 2013;8:e81523.
10.
Won SJ, Jang BG, Yoo BH, Sohn M, Lee MW, Choi BY, Kim JH, Song HK, Suh SW: Prevention of acute/severe hypoglycemia-induced neuron death by lactate administration. J Cereb Blood Flow Metab 2012;32:1086-1096.
11.
Cardinali DP, Srinivasan V, Brzezinski A, Brown GM: Melatonin and its analogs in insomnia and depression. J Pineal Res 2012;52:365-375.
12.
Reiter RJ, Tan DX, Kim SJ, Cruz MH: Delivery of pineal melatonin to the brain and SCN: role of canaliculi, cerebrospinal fluid, tanycytes and Virchow-Robin perivascular spaces. Brain Struct Funct 2014;219:1873-1887.
13.
Reiter RJ, Tan DX, Poeggeler B, Menendez-Pelaez A, Chen LD, Saarela S: Melatonin as a free radical scavenger: implications for aging and age-related diseases. Ann NY Acad Sci 1994;719:1-12.
14.
Chahbouni M, Escames G, Venegas C, Sevilla B, Garcia JA, Lopez LC, Munoz-Hoyos A, Molina-Carballo A, Acuna-Castroviejo D: Melatonin treatment normalizes plasma pro-inflammatory cytokines and nitrosative/oxidative stress in patients suffering from Duchenne muscular dystrophy. J Pineal Res 2010;48:282-289.
15.
Korkmaz A, Ma S, Topal T, Rosales-Corral S, Tan DX, Reiter RJ: Glucose: a vital toxin and potential utility of melatonin in protecting against the diabetic state. Mol Cell Endocrinol 2012;349:128-137.
16.
Cho S, Joh TH, Baik HH, Dibinis C, Volpe BT: Melatonin administration protects CA1 hippocampal neurons after transient forebrain ischemia in rats. Brain Res 1997;755:335-338.
17.
Mesenge C, Margaill I, Verrecchia C, Allix M, Boulu RG, Plotkine M: Protective effect of melatonin in a model of traumatic brain injury in mice. J Pineal Res 1998;25:41-46.
18.
Giusti P, Lipartiti M, Franceschini D, Schiavo N, Floreani M, Manev H: Neuroprotection by melatonin from kainate-induced excitotoxicity in rats. FASEB J 1996;10:891-896.
19.
Manev H, Uz T, Kharlamov A, Joo JY: Increased brain damage after stroke or excitotoxic seizures in melatonin-deficient rats. FASEB J 1996;10:1546-1551.
20.
Rudeen PK, Philo RC, Symmes SK: Antiepileptic effects of melatonin in the pinealectomized Mongolian gerbil. Epilepsia 1980;21:149-154.
21.
Auer RN, Wieloch T, Olsson Y, Siesjo BK: The distribution of hypoglycemic brain damage. Acta Neuropathol 1984;64:177-191.
22.
Schmued LC, Hopkins KJ: Fluoro-Jade: novel fluorochromes for detecting toxicant-induced neuronal degeneration. Toxicol Pathol 2000;28:91-99.
23.
Murakami K, Kondo T, Kawase M, Li Y, Sato S, Chen SF, Chan PH: Mitochondrial susceptibility to oxidative stress exacerbates cerebral infarction that follows permanent focal cerebral ischemia in mutant mice with manganese superoxide dismutase deficiency. J Neurosci 1998;18:205-213.
24.
Zhao H, Kalivendi S, Zhang H, Joseph J, Nithipatikom K, Vasquez-Vivar J, Kalyanaraman B: Superoxide reacts with hydroethidine but forms a fluorescent product that is distinctly different from ethidium: potential implications in intracellular fluorescence detection of superoxide. Free Radic Biol Med 2003;34:1359-1368.
25.
Kauppinen TM, Swanson RA: Poly(ADP-ribose) polymerase-1 promotes microglial activation, proliferation, and matrix metalloproteinase-9-mediated neuron death. J Immunol 2005;174:2288-2296.
26.
Kauppinen TM, Higashi Y, Suh SW, Escartin C, Nagasawa K, Swanson RA: Zinc triggers microglial activation. J Neurosci 2008;28:5827-5835.
27.
Zhou J, Zhang S, Zhao X, Wei T: Melatonin impairs NADPH oxidase assembly and decreases superoxide anion production in microglia exposed to amyloid-β1-42. J Pineal Res 2008;45:157-165.
28.
Marshall KA, Reiter RJ, Poeggeler B, Aruoma OI, Halliwell B: Evaluation of the antioxidant activity of melatonin in vitro. Free Radic Biol Med 1996;21:307-315.
29.
Cazevieille C, Safa R, Osborne NN: Melatonin protects primary cultures of rat cortical neurones from NMDA excitotoxicity and hypoxia/reoxygenation. Brain Res 1997;768:120-124.
30.
Vlkolinsky R, Stolc S: Effects of stobadine, melatonin, and other antioxidants on hypoxia/reoxygenation-induced synaptic transmission failure in rat hippocampal slices. Brain Res 1999;850:118-126.
31.
Skinner DC, Malpaux B: High melatonin concentrations in third ventricular cerebrospinal fluid are not due to Galen vein blood recirculating through the choroid plexus. Endocrinology 1999;140:4399-4405.
32.
Cervantes M, Morali G, Letechipia-Vallejo G: Melatonin and ischemia-reperfusion injury of the brain. J Pineal Res 2008;45:1-7.
33.
Lagneux C, Joyeux M, Demenge P, Ribuot C, Godin-Ribuot D: Protective effects of melatonin against ischemia-reperfusion injury in the isolated rat heart. Life Sci 2000;66:503-509.
34.
Mauriz JL, Molpeceres V, Garcia-Mediavilla MV, Gonzalez P, Barrio JP, Gonzalez-Gallego J: Melatonin prevents oxidative stress and changes in antioxidant enzyme expression and activity in the liver of aging rats. J Pineal Res 2007;42:222-230.
35.
Inamasu J, Suga S, Sato S, Horiguchi T, Akaji K, Mayanagi K, Kawase T: Post-ischemic hypothermia delayed neutrophil accumulation and microglial activation following transient focal ischemia in rats. J Neuroimmunol 2000;109:66-74.
36.
Ziebell JM, Morganti-Kossmann MC: Involvement of pro- and anti-inflammatory cytokines and chemokines in the pathophysiology of traumatic brain injury. Neurotherapeutics 2010;7:22-30.
37.
Won SJ, Kim JH, Yoo BH, Sohn M, Kauppinen TM, Park MS, Kwon HJ, Liu J, Suh SW: Prevention of hypoglycemia-induced neuronal death by minocycline. J Neuroinflammation 2012;9:225.
38.
Ding K, Wang H, Xu J, Lu X, Zhang L, Zhu L: Melatonin reduced microglial activation and alleviated neuroinflammation induced neuron degeneration in experimental traumatic brain injury: possible involvement of mTOR pathway. Neurochem Int 2014;76:23-31.
39.
Lee MY, Kuan YH, Chen HY, Chen TY, Chen ST, Huang CC, Yang IP, Hsu YS, Wu TS, Lee EJ: Intravenous administration of melatonin reduces the intracerebral cellular inflammatory response following transient focal cerebral ischemia in rats. J Pineal Res 2007;42:297-309.
40.
Vilhardt F: Microglia: phagocyte and glia cell. Int J Biochem Cell Biol 2005;37:17-21.
41.
Chhor V, Le Charpentier T, Lebon S, Ore MV, Celador IL, Josserand J, Degos V, Jacotot E, Hagberg H, Savman K, Mallard C, Gressens P, Fleiss B: Characterization of phenotype markers and neuronotoxic potential of polarised primary microglia in vitro. Brain Behav Immun 2013;32:70-85.
42.
Langan SJ, Deary IJ, Hepburn DA, Frier BM: Cumulative cognitive impairment following recurrent severe hypoglycaemia in adult patients with insulin-treated diabetes mellitus. Diabetologia 1991;34:337-344.
© 2015 S. Karger AG, Basel
2015
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.